Conventional vehicle lights include optical systems which are configured such that an LED light source is converted into a laterally long linear light emitting part (see, for example, Japanese Patent Application Laid-Open No. 2007-287490 or corresponding U.S. Pat. No. 7,441,928).
As shown in FIGS. 1A and 1B, a vehicle light 700 described in Japanese Patent Application Laid-Open No. 2007-287490 can be provided with: an LED light source 710; from among the regions produced by dividing the front surface of the LED light source 710 into three regions (an upper region A1, a center region A2, and a lower region A3), a first reflection mirror 721 disposed in the upper region A1; a second reflection mirror 722 disposed on the outside of the first reflection mirror 721; a third reflection mirror 723 disposed in the lower region A3; and a fourth reflection mirror 724 disposed on the outside of the third reflection mirror 723.
According to the vehicle light 700 described in Japanese Patent Application Laid-Open No. 2007-287490 of the aforementioned configuration, the optical paths of light rays L2 from the LED light source 710 which are incident to the first reflection mirror 721 can be changed due to being reflected twice by the first reflection mirror 721 and the second reflection mirror 722, and pass through the right area adjacent to the center region A2 in FIG. 1B. Furthermore, the optical paths of light rays L3 from the LED light source 710 which are incident to the third reflection mirror 723 can be changed due to being reflected twice by the third reflection mirror 723 and the fourth reflection mirror 724, and then pass through the left area adjacent to the center region A2 in FIG. 1B. Due to the light rays L2 and L3 from the LED light source 710 which pass through the respective right and left areas adjacent to the center region A2 after the optical paths thereof have been changed, and the light rays L1 from the LED light source 710 which pass through the center region A2, a laterally long linear light emitting part can be formed, which extends as a whole in one direction (in the lateral left-to-right direction in FIG. 1B).
However, in a vehicle light 700 of the aforementioned configuration, although an LED light source can be converted into a laterally long linear light emitting part, the vehicle light has a disadvantage in that light utilization efficiency is low because the configuration uses mainly light rays of a narrow angle direction with respect to an optical axis from among the light rays emitted from the LED light source 710.
Furthermore, there has also been a disadvantage of further reduced light utilization efficiency as the aforementioned reflection mirrors 721 to 724 which have been subjected to mirror surface processing through sputtering or the like are configured so as to reflect light rays twice and light loss (approximately 30%) may occur as a result of two reflections.